Conventionally, studies have been made about a high electron mobility transistor (HEMT), in which an AlGaN layer and a GaN layer are formed over a substrate by crystal growth and the GaN layer functions as an electron transit layer. The band gap of GaN is 3.4 eV, which is greater than the band gap of Si (1.1 eV) and the band gap of GaAs (1.4 eV). Therefore, the breakdown voltage of the GaN-based HEMT is high and is promising as a high breakdown voltage power device of an automobile or the like.
A HEMT is mainly mounted on a circuit board or the like, on which a gate driver is mounted, and used with connected to the gate driver. In other words, a voltage for ON/OFF control is supplied to the gate of the HEMT from the gate driver via the circuit and the like formed on the circuit board.
However, driving via the circuit and the like formed on the circuit board has a difficulty in operating the HEMT at a sufficiently high speed because of a large inductance component between the gate driver and the HEMT. Further, it is conventionally difficult to house the gate driver and the HEMT in one chip.
Patent Document 1: Japanese National Publication of International Patent Application No. 2004-534380